San Francisco 49ers quarterback Colin Kaepernick (7) looks downfield during the first quarter of his NFL football game against Green Bay Packers at Candlestick Park in San Francisco, Calif. on Saturday, January 12, 2013.

Photo: Stephen Lam, Special To The Chronicle

San Francisco 49ers quarterback Colin Kaepernick (7) looks...

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The "smart guys" on the offensive line have learned to read defenses and can anticipate when quarterback Colin Kaepernick is going to call an audible and what the new play will be.

Photo: Danny Reise, SFC

The "smart guys" on the offensive line have learned to read...

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The San Francisco 49ers offense huddles in-between plays during an NFL football game against the Green Bay Packers Sunday, Sept. 9, 2012, in Green Bay, Wis. By Matt Ludtke/SPECIAL TO THE CHRONICLE

Photo: Matt Ludtke, SFC

The San Francisco 49ers offense huddles in-between plays during an...

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This is a 2012 photo of Joe Staley of the San Francisco 49ers NFL football team. This image reflects the San Francisco 49ers active roster as of Thursday, May 10, 2012 when this image was taken. (AP Photo)

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This is a 2012 photo of Joe Staley of the San Francisco 49ers NFL...

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This is a 2012 photo of Mike Iupati of the San Francisco 49ers NFL football team. This image reflects the San Francisco 49ers active roster as of Thursday, May 10, 2012 when this image was taken. (AP Photo)

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This is a 2012 photo of Mike Iupati of the San Francisco 49ers NFL...

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This is a 2012 photo of Jonathan Goodwin of the San Francisco 49ers NFL football team. This image reflects the San Francisco 49ers active roster as of Monday, June 11, 2012 when this image was taken. (AP Photo)

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This is a 2012 photo of Jonathan Goodwin of the San Francisco 49ers...

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This is a 2012 photo of Alex Boone of the San Francisco 49ers NFL football team. This image reflects the San Francisco 49ers active roster as of Thursday, May 10, 2012 when this image was taken. (AP Photo)

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This is a 2012 photo of Alex Boone of the San Francisco 49ers NFL...

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This is a 2012 photo of Anthony Davis of the San Francisco 49ers NFL football team. This image reflects the San Francisco 49ers active roster as of Thursday, May 10, 2012 when this image was taken. (AP Photo)

If you seek indisputable evidence of professional football's evolution into the 21st century, peer beyond Colin Kaepernick's speed and the read-option and any other cutting-edge toys and ideas in 49ers offensive coordinator Greg Roman's virtual laboratory.

Look no further than the offensive line.

The 49ers, for the 18th consecutive time this season, will send out the same five oversized, underappreciated men for Sunday's NFC Championship Game in Atlanta. Left to right, that's Joe Staley, Mike Iupati, Jonathan Goodwin, Alex Boone and Anthony Davis.

All five weigh at least 300 pounds (all but Boone weigh at least 315). Four of the five stand at least 6-foot-5 (all but Goodwin). All five bring mobility not commonly associated with humans of these dimensions.

Randy Cross understands this better than most observers. Cross started at right guard for the 49ers on their first two Super Bowl teams, then at center for the third. He could move, absolutely, but he stood a modest 6-3, and his playing weight stayed between 265 and 275 pounds for much of his career.

Cross, now a CBS football analyst, marveled as he watched these 49ers offensive linemen demolish their defensive counterparts in last week's divisional playoff victory over Green Bay.

"For years, size was in vogue - you either went really big or gave up some of that size for the ability to move," Cross said in a phone interview this week. "Now there's the next generation of linemen, guys who are 6-4 or 6-5 and 325 to 340 pounds - and can move.

"That's what the 49ers have collected in this group. They do some amazing stuff, and it comes back to their athleticism."

Added versatility

San Francisco's diversity worked to eye-popping perfection against the Packers, whether Kaepernick was running the read-option or setting up camp in the pocket. The 49ers piled up 579 yards in total offense, nicely divided between rushing (323 yards) and passing (256). Kaepernick was sacked only once.

That's an offensive line working in concert.

By all accounts, Iupati - the man-child left guard in his third season from Idaho - qualifies as the best example of the havoc San Francisco causes up front. He's the lineman most prone to penalties, but he's also the one most likely to inspire awestruck reaction among his teammates when they watch video.

Iupati occasionally wanders away from the huddle, Kilgore said, to chat up the defensive linemen he manhandles. It usually happens after Iupati gets beat on a play; apparently he doesn't take kindly to losing even one duel along the line of scrimmage.

Cross noticed while watching video of the win over Green Bay.

"Iupati was born with that edge, that wanting to finish you off," Cross said. "You can teach guys to like to do that, but it's unusual for a guy to do it as second nature. There were a half-dozen times against the Packers where he did exactly that. Guys got a little out of position and off balance - and he just buried them."

Built over time

It took some time for this line to come together and blossom. Staley is the mainstay, a starter since the 49ers drafted him late in the first round in 2007. Iupati and Davis arrived next, both taken in the first round in 2010 and immediately plugged into the lineup.

Goodwin, who helped New Orleans win the Super Bowl after the 2009 season, joined the 49ers as a free agent in August 2011. Boone, undrafted out of Ohio State, became a starter this season, replacing Adam Snyder at right guard.

They bring a wide range of personalities, from Goodwin's professionalism to Staley's loquaciousness to Boone's high volume. Goodwin serves as the ringleader, frequently reining in his young bucks - he's quiet by nature but yelled at his fellow linemen more than usual during the Packers game, filled with playoff adrenaline.

"We have so many different personalities, and somehow it all comes together," Boone said. "It's like five brothers just kind of hanging out."

They hung out in a new realm against Green Bay, leaning on the read-option as if it were a longtime staple of the offense. It's not, even if the 49ers have worked on it in practice much of the season.

Still, the smashing success of those plays speaks to more than Kaepernick's dynamic skills. It also reflects well on the linemen, who adapted without much trouble.

"We've got some smart guys, so we're able to adjust," Goodwin said.

That wisdom results, in part, from offensive line coach Mike Solari's endless meetings. More than one lineman pointed to those meetings as vital, because deep understanding of the offense allows for smooth improvisation at the line of scrimmage.

It has reached the point, Boone said, where he and his cohorts approach the line, see the defensive formation and quickly tell each other which audible is coming. Then, when Kaepernick calls the exact audible they expected, the linemen laugh as they await the snap.

Noise factor

The 49ers need their offense to work in this kind of unison Sunday, given the noise they will confront in the Georgia Dome. That puts an extra burden on the offensive line in trying to usher the 49ers to their first Super Bowl in 18 years.

Goodwin and Co. will enjoy a decided advantage in heft against the Falcons, who average 278 pounds on their defensive line and feature no players at 300-plus.

Cross, as you would expect of a former offensive lineman, eagerly awaits this tussle. He takes pride in seeing his 49ers descendants on the brink of another Super Bowl, and he takes particular pride in knowing the offensive line is one big reason.

He also knows this year's line, equally adept at power and speed, is nothing like the lines on which he played in the 1980s.

"This is a different kind of 49ers - they go after people at the line of scrimmage," Cross said. "It's a team that wants to stand toe-to-toe, if people are dumb enough to do it."

It's what's up front that counts

The 49ers have one of the NFL's best offensive lines - with a distinct mix of personalities. Here's a quick look at each starter, with good-natured quotes from backup guard Daniel Kilgore:

Joe Staley

Left tackle

6-foot-5,

315 pounds

6th season (Central Michigan)

Kilgore: "Staley likes the camera. He likes everybody to know he's an athlete. He's very vocal when he has a chance to be."

Mike Iupati

Left guard

6-foot-5,

331 pounds

3rd season (Idaho)

Kilgore: "He's the biggest human on the O-line. He's a blockhead, a hardhead, but he's probably the biggest teddy bear."

Jonathan Goodwin

Center

6-foot-3,

318 pounds

11th season (Michigan)

Kilgore: "Jon is the captain, the brainiac, the commander. He runs the whole show."